A worm reduction gear generally comprises a worm shaft carrying a worm and lying orthogonal to a worm-wheel shaft on which a worm wheel is keyed to mesh with the worm. Both shafts are journaled in a housing which is usually specially designed for the particular application to which the reduction gearing is to be put.
Such systems lack versatility, generally make use of expensive housing structures and are largely unsatisfactory for other reasons as well.